A known example of a conventional railcar damping device is interposed between a vehicle body and a truck of a railcar and used to suppress left-right direction vibration relative to an advancement direction.
JP2010-65797A discloses a railcar damping device including: a cylinder coupled to either a truck or a vehicle body of a railcar; a piston inserted into the cylinder to be free to slide; a rod inserted into the cylinder and coupled to the other of the truck and the vehicle body and to the piston; a rod side chamber and a piston side chamber defined within the cylinder by the piston; a tank storing a liquid that is supplied to the cylinder; a first opening/closing valve provided midway in a first passage that connects the rod side chamber to the piston side chamber; a second opening/closing valve provided midway in a second passage that connects the piston side chamber to the tank; a pump that supplies working oil to the rod side chamber; an exhaust passage that connects the rod side chamber to the tank; and a variable relief valve that is provided midway in the exhaust passage and has a modifiable valve opening pressure. By driving the pump, the first opening/closing valve, the second opening/closing valve, and the variable relief valve, an actuator can generate thrust in both an expansion direction and a contraction direction, and vibration of the vehicle body is suppressed by this thrust.